Abstract

Identifying drought tolerant genotypes is very important for increasing corn yield. Thus four simple corn hybrids were submitted to periods of water shortage, at three phenological stages of the crop, to discriminate for drought tolerance by principal components analysis and identify their main differentiating characteristics under limited water conditions. Assessments were made of the leaf water potential, gas exchange, photochemical activity, grain yield and total dry matter. Analysis of variance was carried out and the mean values were compared by the Tukey test at 5% probability. Water shortage at the three phenological stages of the corn crop reduced the leaf water potential (Ψw), stomata conductance (gs), photosynthesis (Ai), transpiration (Ei), potential quantum efficiency of the PSII (Fv/Fm), apparent rate of electron transport (ETR), photochemical dissipation coefficient (qP) and increased the non-photochemical dissipation coefficient (NPQ), mainly when there was drought at the vegetative and flower¬ing stages. The data obtained for grain yield (GY) showed that the TOL1 hybrid was outstanding for drought toler¬ance at all the phenological stages of the crop, while the SENS1 hybrid demonstrated greatest sensitivity to water shortage, proving the pattern of tolerance and sensitivity of these respective hybrids to drought. The result of the principal components analysis showed that the corn hybrids could be separated into diversity groups for irrigation treatment at the vegetative stage, and that integrated photosynthesis (Ai) was considered the best characteristic to discriminate the irrigation treatments and hybrids when submitted to water shortage at this phenological stage of the crop.